HIGH RESOLUTION ELECTROMECHANICAL MAPPING OF THE HEART We have continued to develop the hardware, MR pulse sequences and data analysis software to perform high resolution mechanical function maps while simultaneously recording electrical activation maps from an electrode "sock" surrounding the heart. We have also developed the hardware to perform endocardial mapping simultaneously with the epicardial mapping using a basket electrode. The electrical recording system has been made MR compatible so that the MR image quality is not degraded by the presence of the sock around the heart. Coupled electromechanical activation maps are being generated by registration of the electrical maps with the mechanical maps generated from MRI tagging studies. An infarct model has been studied relating the location and morphological severity of infact with both the electrical abnormality and the mechanical abnormality; in particular, a model of sustained ventricular tachycardia has been achieved. Re-entrant ventricular tachycardia has been captured with electrical measurments and realtime MRI measurements.